It not only resolved his dilemma but has also left behind a remarkable legacy now preserved by the British Film Institute.

After part of a day spent filming children playing in the semi-derelict streets and wastelands of Nechells, ‘They Took Them To The Sea’ was shot during a demanding 12-hour shoot the next day.

But it was tough in more ways than one.

“The NSPCC film was meant to be a money-raiser to show to nice children in nice schools,” says John.

“It was for The Children’s League of Pity – Junior Section. But how could I make a film about child cruelty and not show it? That raised a problem.

“I joined the NSPCC inspectors for a week and the more I saw – and smelled – the further away I was from getting the idea of how to make the film.

“We couldn’t make a film about a crowd of children, so we needed to concentrate on just some of them.

“When we arrived in Birmingham the day before, we took them for a tea party in a hotel and it was the weirdest, strangest, most upsetting tea party.

“You would expect it to be nice. Exciting.

“But some of the children were so damaged that they could not enjoy the moment.

“The silence at the tea party was extraordinary.

“I had no idea it was going to be like that, but I was glad I held it.”

To get them onside, he let them explore the cameras through play, and each of the four cameramen was then assigned to concentrate on a particular child.

The children were from different districts under the care of four NSPCC inspectors.

“In the scene where they are having labels attached, we were asked to make sure that nobody could read their names on the screen to keep them anonymous,” he recalls. “Some of the children had been neglected.

“Others gave the sense of having been ill-treated.

A scene from the NSPCC commissioned film by John Krish, They Took Us To The Sea

“This was an era when things could be dark at a family level, but you didn’t talk about it. In my childhood, for example, nobody ever mentioned the word ‘cancer’ unless it was whispered.

“I made the children promise not to look at the camera throughout the day and I said I would not spoil their day. We kept our promises.

“Starting out, there wasn’t much excitement, but their character really comes out when they are on the donkeys and at the funfair.

“And some of their reactions when they are eating are very telling.

“Some of them had a hangdog look at the station, which was very disturbing for me.

“After the shoot, I waved goodbye to them,” he recalls. “But I couldn’t eat. I was so drained.”

In addition to the footage, John wrote eight lines of dialogue which a boy who was not in the film narrated for him. They included ‘Never seen the sea before. It’s got a funny smell to it’.

Many of the children had never been out of Birmingham before.

“Making the film was an extraordinary experience,” says John. “When we got back, I just had to get on a train to London. I stood up in the corridor the whole way there, with the window open so that the wind would blow on my face. I was exhausted.

“Later, we watched the silent footage in the lab. It was incredibly moving.”

John was no stranger to the emotional punch packed by documentary film.

Invalided out of the Army, he had made films with the American Office of War Information News Feed.

One day, four hours of material arrived. John and his colleagues were stunned when they watched the footage.

It was of the liberation of Dachau concentration camp.

The harrowing scenes were chilling, the horror depicted in them something a man in his early 20s had no idea could possibly exist.

“Seeing that was devastating. Horrifying,” says John in a manner that tells you all you need to know about his reluctance to talk about his Birmingham film after darkness falls.

After making the NSPCC film, he was asked to direct top TV show The Avengers when it switched from black and white to colour.

“I declined,” he says.

John Krish

“They wanted them turned around so fast I wouldn’t have been able to cast one while still editing another.

“We compromised, and I created the cool atmosphere of the end credits at the front and end instead.”

John also directed Roger Moore in The Saint.

“He was a very sweet man, who always knew his lines,” he recalls. “But as Bond? I wasn’t convinced by him. To me, he comes across as very weak. Daniel Craig is the best Bond, much better than any of them.”

John is steadfast in his belief in the power of film, and not shy of rocking the boat. He quit BAFTA in the mid 1960s in protest at My Fair Lady being made best film ahead of Zorba The Greek.

And he is remarkably engaging after what he calls his ‘wonderful life’.

Still desperately sad that his wife died from cancer two years ago at the age of 75, he doesn’t even make films of his nine grandchildren.

Son Justin, 54, is a respected film editor with Aardman, having borrowed his dad’s 8mm camera as an eight-year-old to start filming his sisters.

Rachel works in finance for Channel 4, Julia is a barrister and John thinks only one of his grandchildren might want to follow him into films.

“I wish Justin had been old enough to edit my films, he’s so good,” says John.

“Am I still ‘young’? If I am, I don’t put that down to the film industry, where betrayal is endemic and like walking into a minefield.

“Making documentaries was more pleasurable, but they didn’t pay well.

“Having started in the industry at 16-and-a-half, I left it after 50 years, although it was a job I believe I was born to do.

“I lasted a fortnight in a job with an estate agent and became a clerk in a Peak Freans biscuit factory – and absolutely no way was I born to do that.